Flexible ROADM-less optical hub and spoke node architecture for coherent transponders

Abstract

One embodiment provides a network node of a metro optical network that includes first and second optical filters. The first optical filter is configured to pass wavelength channels in a first wavelength band and block wavelength channels in a non-overlapping second wavelength band. The second optical filter is configured to block wavelength channels of the first wavelength band and pass wavelength channels of the second wavelength band. An optical splitter is configured to split a received optical signal into first and second signal portions and to direct the first signal portion to the first optical filter. An optical combiner is configured to combine output of the second optical filter with the second signal portion from the optical splitter. An optical transceiver is configured to recover data from a first wavelength channel passed by the first optical filter, and to output a second wavelength channel passed by the second optical filter.

The invention claimed is: 
     
       1. An apparatus, comprising:
 a first optical splitter configured to split a received wavelength-division multiplexed (WDM) optical signal into first and second signal portions; 
 a first high-pass optical filter configured to pass shorter-wavelength channels of the first signal portion in a first wavelength band and to block longer-wavelength channels of the first signal portion in a non-overlapping second wavelength band, a shortest-wavelength channel of said second wavelength band being longer than a longest-wavelength channel of said first wavelength band 
 a first low-pass optical filter configured to block the shorter-wavelength channels and to pass the longer-wavelength channels; and 
 an optical combiner configured to combine the second signal portion with an added wavelength channel passed by the first low-pass optical filter. 
 
     
     
       2. The apparatus of  claim 1 , further comprising an optical transponder configured to recover data from a selected wavelength channel passed by the first high-pass optical filter. 
     
     
       3. The apparatus of  claim 1 , further comprising:
 a second optical splitter configured to split an output of the combiner into third and fourth signal portions; and 
 a second high-pass optical filter configured to pass the shorter-wavelength channels of the third signal portion and to block the longer-wavelength channels of the third signal portion. 
 
     
     
       4. The apparatus of  claim 3 , further comprising:
 a second low-pass optical filter configured to block the shorter wavelength channels and to pass the longer-wavelength channels; and 
 a second optical combiner configured to combine the fourth signal portion with an added wavelength channel passed by the second low-pass optical filter. 
 
     
     
       5. The apparatus of  claim 4 , further comprising:
 a first optical transmitter configured to output a first longer-wavelength channel in the second wavelength band to the first low-pass optical filter; and 
 a second optical transmitter configured to output a second longer-wavelength channel in the second wavelength band to the second low-pass optical filter. 
 
     
     
       6. A system, comprising:
 first and second low-pass optical filters configured to block wavelength channels of a first wavelength band of a wavelength-division multiplexed (WDM) optical signal and to pass wavelength channels of a second wavelength band of said WDM optical signal, a shortest-wavelength channel of said second wavelength band being longer than a longest-wavelength channel of said first wavelength band; 
 a first optical transmitter configured to direct a first wavelength channel of the second wavelength band to the first low-pass optical filter; 
 a second optical transmitter configured to direct a second wavelength channel of the second wavelength band to the second low-pass optical filter; 
 an optical combiner configured to combine the first and second wavelength channels 
 a high-pass optical filter configured to pass wavelength channels of the first wavelength band and to block wavelength channels of the second wavelength band; and 
 an optical splitter configured to split output of the first low-pass optical filter into a first signal portion directed toward the high-pass optical filter and a second signal portion directed toward the optical combiner. 
 
     
     
       7. A method, comprising:
 configuring a first optical splitter to split a wavelength-division multiplexed (WDM) optical signal into first and second signal portions; 
 configuring a high-pass optical filter to receive the first signal portion, wherein the high-pass optical filter is configured to pass shorter-wavelength channels of the WDM optical signal and to block longer-wavelength channels of the WDM optical signal, a shortest-wavelength channel of said second wavelength band being longer than a longest-wavelength channel of said first wavelength band 
 configuring a first low-pass optical filter, adapted to block the shorter-wavelength channels and to pass the longer-wavelength channels, to receive a first added wavelength channel in the second wavelength band; and 
 configuring an optical combiner to combine the second signal portion with the first added wavelength channel passed by the first low-pass optical filter. 
 
     
     
       8. The method of  claim 7 , further comprising configuring an optical transponder to recover data from a selected one of the shorter-wavelength channels passed by the high-pass optical filter. 
     
     
       9. The method of  claim 7 , further comprising:
 configuring a second optical splitter to split the output of the combiner into third and fourth signal portions; and 
 configuring a second high-pass optical filter to receive the third signal portion, the second high-pass optical filter being adapted to pass wavelength channels in the first wavelength band and block wavelength channels in the second wavelength band. 
 
     
     
       10. The method of  claim 9 , further comprising:
 configuring a second low-pass optical filter to receive a second added-wavelength channel in the second wavelength band, the second low-pass optical filter being adapted to block said shorter-wavelength channels and to pass said longer-wavelength channels; and 
 configuring a second optical combiner to combine said second added wavelength channel with the fourth signal portion. 
 
     
     
       11. The method of  claim 10 , further comprising:
 configuring a first optical transmitter to output a first longer-wavelength channel to the first low-pass optical filter; and 
 configuring a second optical transmitter to output a second longer wavelength channel to the second low-pass optical filter. 
 
     
     
       12. A method, comprising:
 configuring a first low-pass optical filter to receive a first added-wavelength channel from a first optical transmitter, the first low-pass optical filter being adapted to block shorter-wavelength channels and to pass longer-wavelength channels; 
 configuring a second low-pass optical filter to receive a second added-wavelength channel from a second optical transmitter, the second low-pass optical filter being adapted to block said shorter-wavelength channels and to pass said longer-wavelength channels; 
 configuring an optical combiner to combine the first and second added wavelength channels passed by the first and second low-pass optical filters; 
 configuring an optical splitter to split output of the first optical filter into a first signal portion directed to the combiner and a second signal portion; and 
 configuring a high-pass optical filter to receive the second signal portion, the high-pass optical filter being adapted to pass said shorter wavelength channels and block said longer wavelength channels. 
 
     
     
       13. A network node of a metro optical network, comprising:
 a high-pass optical filter configured to pass shorter-wavelength channels of a received wavelength-division multiplexed (WDM) optical communication signal and to block longer-wavelength channels of the WDM signal; 
 an optical splitter configured to split a received optical signal into first and second signal portions and to direct the first signal portion to the high-pass optical filter; 
 a low-pass optical filter configured to block said shorter-wavelength channels and to pass said longer-wavelength channels; 
 an optical combiner configured to combine output of the low-pass optical filter with the second signal portion from the optical splitter; 
 an optical receiver configured to recover data from a first selected one of said shorter-wavelength channels passed by the high-pass optical filter; and 
 an optical transmitter configured to direct to the low-pass optical filter a second selected one of said longer-wavelength channel. 
 
     
     
       14. An apparatus, comprising:
 a first optical splitter configured to split a received wavelength-division multiplexed (WDM) optical signal into first and second signal portions; 
 a first low-pass optical filter configured to pass redder-wavelength channels of the first signal portion in a first wavelength band and to block bluer-wavelength channels of the first signal portion in a second wavelength band, a longest-wavelength channel of said second wavelength band being shorter than a shortest-wavelength channel of said first wavelength band; 
 a first high-pass optical filter configured to block the redder-wavelength channels and to pass the bluer-wavelength channels; and 
 an optical combiner configured to combine the second signal portion with an added wavelength channel passed by the first high-pass optical filter. 
 
     
     
       15. The apparatus of  claim 14 , further comprising an optical transponder configured to recover data from a selected wavelength channel passed by the first low-pass optical filter. 
     
     
       16. The apparatus of  claim 14 , further comprising:
 a second optical splitter configured to split an output of the optical combiner into third and fourth signal portions; and 
 a second low-pass optical filter configured to pass the redder-wavelength channels of the third signal portion and to block the bluer-wavelength channels of the third signal portion. 
 
     
     
       17. The apparatus of  claim 16 , further comprising:
 a second high-pass optical filter configured to block the redder-wavelength channels and to pass the bluer-wavelength channels; and 
 a second optical combiner configured to combine the fourth signal portion with an added wavelength channel passed by the second high-pass optical filter. 
 
     
     
       18. The apparatus of  claim 17 , further comprising:
 a first optical transmitter configured to output a first bluer-wavelength channel in the second wavelength band to the first high-pass optical filter; and 
 a second optical transmitter configured to output a second bluer-wavelength channel in the second wavelength band to the second high-pass optical filter. 
 
     
     
       19. A system, comprising:
 first and second high-pass optical filters configured to block wavelength channels of a first wavelength band of a wavelength-division multiplexed (WDM) optical signal and to pass wavelength channels of a second wavelength band of said WDM optical signal, a longest-wavelength channel of said second wavelength band being shorter than a shortest-wavelength channel of said first wavelength band; 
 a first optical transmitter configured to direct a first wavelength channel of the second wavelength band to the first high-pass optical filter; 
 a second optical transmitter configured to direct a second wavelength channel of the second wavelength band to the second high-pass optical filter; 
 an optical combiner configured to combine the first and second wavelength channels; 
 a low-pass optical filter configured to pass wavelength channels of the first wavelength band and to block wavelength channels of the second wavelength band; and 
 an optical splitter configured to split output of the first high-pass optical filter into a first signal portion directed toward the low-pass optical filter and a second signal portion directed toward the optical combiner. 
 
     
     
       20. A method, comprising:
 configuring a first optical splitter to split a wavelength-division multiplexed (WDM) optical signal into first and second signal portions; 
 configuring a low-pass optical filter to receive the first signal portion, wherein the low-pass optical filter is configured to pass longer-wavelength channels in a first wavelength band of the WDM optical signal and to block shorter-wavelength channels in a second wavelength band of the WDM optical signal, a longest-wavelength channel of said second wavelength band being shorter than a shortest-wavelength channel of said first wavelength band; 
 configuring a first high-pass optical filter, adapted to block the longer-wavelength channels and to pass the shorter-wavelength channels, to receive a first added wavelength channel in the second wavelength band; and 
 configuring an optical combiner to combine the second signal portion with the first added wavelength channel passed by the first high-pass optical filter. 
 
     
     
       21. The method of  claim 20 , further comprising configuring an optical transponder to recover data from a selected one of the longer-wavelength channels passed by the low-pass optical filter. 
     
     
       22. The method of  claim 20 , further comprising:
 configuring a second optical splitter to split the output of the optical combiner into third and fourth signal portions; and 
 configuring a second low-pass optical filter to receive the third signal portion, the second low-pass optical filter being adapted to pass wavelength channels in the first wavelength band and block wavelength channels in the second wavelength band. 
 
     
     
       23. The method of  claim 22 , further comprising:
 configuring a second high-pass optical filter to receive a second added-wavelength channel in the second wavelength band, the second high-pass optical filter being adapted to block said longer-wavelength channels and to pass said shorter-wavelength channels; and 
 configuring a second optical combiner to combine said second added wavelength channel with the fourth signal portion. 
 
     
     
       24. The method of  claim 23 , further comprising:
 configuring a first optical transmitter to output a first shorter-wavelength channel to the first high-pass optical filter; and 
 configuring a second optical transmitter to output a second shorter wavelength channel to the second high-pass optical filter. 
 
     
     
       25. A method, comprising:
 configuring a first high-pass optical filter to receive a first added-wavelength channel from a first optical transmitter, the first high-pass optical filter being adapted to block longer-wavelength channels and to pass shorter-wavelength channels; 
 configuring a second high-pass optical filter to receive a second added-wavelength channel from a second optical transmitter, the second high-pass optical filter being adapted to block said longer-wavelength channels and to pass said shorter-wavelength channels; 
 configuring an optical combiner to combine the first and second added wavelength channels passed by the first and second high-pass optical filters; 
 configuring an optical splitter to split output of the first optical filter into a first signal portion directed to the combiner and a second signal portion; and 
 configuring a low-pass optical filter to receive the second signal portion, the low-pass optical filter being adapted to pass said longer wavelength channels and block said shorter wavelength channels. 
 
     
     
       26. A network node of a metro optical network, comprising:
 a low-pass optical filter configured to pass longer-wavelength channels of a received wavelength-division multiplexed (WDM) optical communication signal and to block shorter-wavelength channels of the WDM signal; 
 an optical splitter configured to split a received optical signal into first and second signal portions and to direct the first signal portion to the first low-pass optical filter; 
 a high-pass optical filter configured to block said longer-wavelength channels and to pass said shorter-wavelength channels; 
 an optical combiner configured to combine output of the high-pass optical filter with the second signal portion from the optical splitter; 
 an optical receiver configured to recover data from a first selected one of said longer-wavelength channels passed by the low-pass optical filter; and 
 an optical transmitter configured to direct to the high-pass optical filter a second selected one of said shorter-wavelength channel.